Conservative MP Nadine Dorries says the government’s same-sex marriage bill will take the “sex out of marriage” and wonders whether a sister could marry a sister in order to avoid inheritance tax as part of the reform.

Warning that the bill could result in the Conservatives losing “as many as fifty seats” at the next general election, the MP cited a Telegraph article by Charles Moore, the paper’s former editor and Lady Thatcher’s official biographer.

Moore wrote: “With gay marriage, the Coalition proposes to alter fundamentally the most important social structure ever known to mankind. If it hopes to slip this quietly past the country over the summer, without any serious consequences, it is being not only dishonest, but stupid.”

Moore then argues that the bill is flawed because it does not stipulate requirements for consummation or divorce.

“The government is introducing, for the first time, a definition of marriage which has no sexual element,” Moore says. “Yet it refuses to face the logical consequence of this surprising innovation. If sexual intercourse is not part of the definition of same-sex marriage, why should blamelessly cohabiting sisters not marry one another in order to avoid inheritance tax? Why should father not marry son?

“Why shouldn’t heterosexual bachelor chum marry heterosexual bachelor chum? What, come to think about it, is so great about the idea of monogamy, once sex and children are removed from the equation? Does the word ‘marriage’ any longer contain much meaning?”